Assembly and disassembly dynamics of the cyanobacterial periodosome
Assembly and disassembly dynamics of the cyanobacterial periodosome
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DOI：
10.1016/j.molcel.2008.01.015
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发表时间：
2008-03-28
期刊：
影响因子：
16
通讯作者：
Maeda, Yuichiro
中科院分区：
文献类型：
--
作者：
Akiyama, Shuji;Nohara, Atsushi;Maeda, Yuichiro
在体外，三种KAI蛋白KaIA、Kaib和KaiC与三磷酸腺苷一起诱导KaiC磷酸化循环，这是一种潜在的蓝藻细长聚球藻PCC7942的昼夜节律起搏器。KAI蛋白组装成大的异质多聚体复合体(牙周体)，以实现KaiC磷酸化的强劲振荡。在这里，我们报道了用小角X射线散射法实时测量KAI牙周体的组装/拆解动力学，并确定了KaIA：KaiC和Kaib：KaiC复合体的低分辨形状。大多数以前发现的影响周期的突变可以映射到我们复杂模型的关联界面上。我们的结果表明，组装/拆卸过程在同步化早期对相夹带是至关重要的，但在振荡后期则被动地受到KaiC的磷酸化状态的驱动。KAI牙周体的组装方式是这样一种方式，即KaIA和Kaib以磷酸化依赖的方式被招募到KaiC的C-末端区域。
In vitro incubation of three Kai proteins, KaiA, KaiB, and KaiC, with ATP induces a KaiC phosphorylation cycle that is a potential circadian clock pacemaker in cyanobacterium Synechococcus elongatus PCC 7942. The Kai proteins assemble into large heteromultimeric complexes (periodosome) to effect a robust oscillation of KaiC phosphorylation. Here, we report real-time measurements of the assembly/disassembly dynamics of the Kai periodosome by using small-angle X-ray scattering and determination of the low-resolution shapes of the KaiA:KaiC and KaiB:KaiC complexes. Most previously identified period-affecting mutations could be mapped to the association interfaces of our complex models. Our results suggest that the assembly/disassembly processes are crucial for phase entrainment in the early synchronizing stage but are passively driven by the phosphorylation status of KaiC in the late oscillatory stage. The Kai periodosome is assembled in such a way that KaiA and KaiB are recruited to a C-terminal region of KaiC in a phosphorylation-dependent manner.